When a machine builder or maintenance engineer finds that an encoder model is no longer available, the first reaction is often to search for the exact part number. In many cases the original is discontinued, and the search leads nowhere. The faster path is cross-referencing: identifying the technical attributes that define the device and matching them to a current alternative.
This article walks through what to read from the nameplate and how to turn it into a replacement specification.
What the nameplate tells you
Most rotary encoders carry a label with the parameters that actually matter for interchangeability. Capture the following before looking for a substitute:
| Parameter | Why it matters |
|---|---|
| Shaft diameter and type | Must match the mechanical coupling (solid vs hollow shaft, 6/8/10/12 mm etc.) |
| Resolution (PPR / bits) | Defines position feedback accuracy; incremental is pulses per revolution, absolute is bits |
| Output type | Incremental (A/B/Z) vs absolute (SSI, BiSS, parallel, fieldbus) |
| Supply voltage | Typically 5 V, 12 V or 24 V DC |
| Mounting / flange | Synchro, clamp, servoflange or through-hollow — affects fit |
| Electrical interface | Push-pull, line driver (RS422), open collector |
| Protection rating | IP degree, relevant for harsh or wash-down environments |
| Cable or connector | Exit direction and pinout, or M12/M23 connector |
A photo of the nameplate plus the mounting dimensions is usually enough for a specialist to propose a match.
Incremental vs absolute
The two families are not interchangeable by default. An incremental encoder outputs relative pulses and loses position after a power cycle unless the system re-homes. An absolute encoder retains position and is used where losing the reference is not acceptable. Confirm which one your controller expects before substituting.
How a cross-reference is built
- Record the original part number and capture the nameplate photo.
- List the six mechanical and electrical attributes above.
- Match resolution and output first, then voltage and mounting.
- Verify the connector or cable pinout.
- Validate the candidate on the bench or in a non-critical position before full rollout.
Why use a sourcing specialist
A single encoder may be offered by several manufacturers with equivalent specifications — for example FENAC, ELTRA, LIKA or Hengstler cover common incremental and absolute types. A sourcing partner keeps multiple brands on file, checks the candidate against your nameplate, supplies procurement documentation, and can often ship a stocked equivalent within a day or two rather than waiting on a long factory lead time.
Get a quote
If you have an encoder number — current or obsolete — send it to us with a nameplate photo. We return a cross-reference suggestion, price and lead time, typically within one business day.
- Browse the FENAC encoder range we carry.
- Or go straight to the inquiry form.